The purpose of this study is to conduct a natural history study, characterizing the pulmonary and cardiac disorders resulting from vertically transmitted (mother-to-child during gestation or the perinatal time period) human immunodeficiency virus (HIV) in children. Two groups will be studied. The first group will define cardiopulmonary structure, growth and function in the prenatal and early childhood period. The second group will determine the types, incidence, course and outcome of cardiopulmonary disorders.